Automatic firearm

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A M2 Browning machine gun, surrounded by ejected cartridge cases M2 machine gun.jpg
A M2 Browning machine gun, surrounded by ejected cartridge cases

An automatic firearm or fully automatic firearm (to avoid confusion with semi-automatic firearms) is a self-loading firearm that continuously chambers and fires rounds when the trigger mechanism is actuated. The action of an automatic firearm is capable of harvesting the excess energy released from a previous discharge to feed a new ammunition round into the chamber, and then igniting the propellant and discharging the projectile (either bullet, shot, or slug) by delivering a hammer or striker impact on the primer.

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If both the feeding and ignition procedures are automatically cycled, the weapon will be considered "fully automatic" and will fire continuously as long as the trigger is kept depressed and the ammunition feeding (either from a magazine or a belt) remains available. In contrast, a firearm is considered "semi-automatic" if it only automatically cycles to chamber new rounds (i.e. self-loading) but does not automatically fire off the shot unless the user manually resets (usually by releasing) and re-actuates the trigger, so only one round gets discharged with each individual trigger-pull. [1] A burst-fire firearm is an "in-between" of fully and semi-automatic firearms, firing a brief continuous "burst" of multiple rounds with each trigger-pull, but then will require a manual re-actuation of the trigger to fire another burst.

Automatic firearms are further defined by the type of cycling principles used, such as recoil operation, blowback, blow forward, or gas operation.

Rates of fire

Cyclic rate

Self-loading firearms are designed with varying rates of fire due to having different purposes. The speed with which a self-loading firearm can cycle through the functions of:

  1. Fire
  2. Eject
  3. Load
  4. Cock

is referred to as its cyclic rate. In fully automatic firearms, the cyclic rate is tailored to the purpose the firearm is intended to serve. Anti-aircraft machine guns often have extremely high rates of fire to maximize the probability of a hit. In infantry support weapons, these rates of fire are often much lower and in some cases, vary with the design of the particular firearm. The MG 34 is a WWII-era machine gun which falls under the category of a "general purpose machine gun". It was manufactured in several variations: with a cyclic rate as high as 1200 rounds per minute, but also in an infantry model which fired at 900 rounds per minute. [2]

Effective rate of fire

Continuous fire generates high temperatures in a firearm's barrel and increased temperatures throughout most of its structure. If fired continuously, the components of the firearm will eventually suffer structural failure. All firearms, whether they are semi-automatic, fully automatic, or otherwise, will overheat and fail if fired indefinitely. This issue tends to present itself primarily with fully automatic fire. For example, the MG34 may have a calculated cyclic rate of 1200 rounds per minute, but is likely to overheat and fail in the space of one minute of continuous fire. [3]

Semi-automatic firearms may also overheat if continuously fired. Recoil plays a significant role in the time it takes to reacquire one's sight picture, ultimately reducing the effective rate of fire. [4]

Automatic firearm types

A United States Army soldier laying automatic suppressive fire with an M60 machine gun during the Vietnam War NARA 111-CCV-345-CC37981 25th Infantry Division soldier spraying tree line with M60 fire Operation Cedar Falls 1967.jpg
A United States Army soldier laying automatic suppressive fire with an M60 machine gun during the Vietnam War

Automatic firearms can be divided into six main categories:

Automatic rifle
The standard type of service rifles in most modern militaries, usually capable of selective fire. Assault rifles are a specific type of select-fire rifle chambered in an intermediate cartridge and fed via a high-capacity detachable magazine. Battle rifles are similar, but chambered in a full-powered cartridge. [5]
Automatic shotgun
A type of combat shotgun capable of firing shotgun shells automatically, usually also semi-automatically. [5]
Machine gun
A large group of heavier firearms used for suppressive automatic fire of rifle cartridges, usually attached to a mount or supported by a bipod. Depending on size, weight and role, machine guns are divided into heavy, medium or light machine guns. The ammunition is often belt-fed. [5]
Submachine gun
An automatic, short rifle (carbine) typically chambered for pistol cartridges. Today seldom used in military contexts due to a rise in the use of body armor, they are commonly used by police forces and close protection units in many parts of the world. [5]
Personal defense weapon
A new breed of automatic firearms that combines the light weight and size of the submachine gun with the medium power caliber ammunition of the rifle, thus in practice creating a submachine gun with body armor penetration capability. [5]
Machine pistol
A handgun-style firearm, capable of fully automatic or burst fire. They are sometimes equipped with a foldable shoulder stock, to promote accuracy during automatic fire, creating similarities to their submachine gun counterparts. Some machine pistols are shaped similarly to semi-automatics (e.g., the Glock 18, Beretta 93R). As with SMGs, machine pistols fire pistol caliber cartridges (such as the 9mm, .40, .45 ACP etc.). [5]

Burst mode

Burst mode is an automatic fire mode that limits the number of rounds fired with each trigger pull, most often to three rounds. After the burst is fired, the firearm will not fire again until the trigger is released and pulled again. Burst mode was implemented into firearms due to the inaccuracy of fully automatic fire in combat, and due to suggestions that fully automatic fire has no genuine benefit. Additionally, many militaries have restricted automatic fire in combat due to the ammunition wasted. [6]

Regulation

Possession of automatic firearms tends to be restricted to members of military and law enforcement organizations in most developed countries, even in those that permit the civilian use of semi-automatic firearms. Where automatic weapons are permitted, restrictions and regulations on their possession and use may be much stricter than for other firearms. [1] In the United States, taxes and strict regulations affect the manufacture and sale of fully automatic firearms under the National Firearms Act of 1934 and the Firearm Owners Protection Act of 1986; the latter act closed the "machine gun" registry to new registrations, meaning that only previously registered automatic weapons may be purchased. A prospective user must go through an application process administered by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), which requires a federal tax payment of $200 and a thorough criminal background check. The tax payment buys a revenue stamp, which is the legal document allowing possession of an automatic firearm. The use of a gun trust to register with the ATF has become an increasingly popular method of acquisition and ownership of automatic firearms.[ why? ]

Similar weapons

Other similar weapons not usually referred to as automatic firearms include the following:

See also

Related Research Articles

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A firearm is any type of gun that uses an explosive charge and is designed to be readily carried and used by an individual. The term is legally defined further in different countries.

<span class="mw-page-title-main">Machine gun</span> Fully-automatic firearm

A machine gun (MG) is a fully automatic, rifled auto-loading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles are typically designed more for firing short bursts rather than continuous firepower and are not considered true machine guns. Submachine guns fire handgun cartridges rather than rifle cartridges, therefore they are not considered machine guns, while automatic firearms of 20 mm (0.79 in) caliber or more are classified as autocannons rather than machine guns.

<span class="mw-page-title-main">Machine pistol</span> Fully automatic handgun

A machine pistol is an autoloading pistol capable of fully automatic fire, including stockless handgun-style submachine guns.

<span class="mw-page-title-main">Action (firearms)</span> Functional mechanism of breech-loading

In firearms terminology, an action is the functional mechanism of a breech-loading firearm that handles the ammunition cartridges, or the method by which that mechanism works. Actions are technically not present on muzzleloaders, as all those are single-shot firearms with a closed off breech with the powder and projectile manually loaded from the muzzle. Instead, the muzzleloader ignition mechanism is referred to as the lock.

The MG 34 is a German recoil-operated air-cooled general-purpose machine gun, first tested in 1929, introduced in 1934, and issued to units in 1936. It introduced an entirely new concept in automatic firepower – the Einheitsmaschinengewehr – and is generally considered the world's first general-purpose machine gun (GPMG). Both the MG 34 and MG 42 were erroneously nicknamed "Spandau" by Allied troops, a carryover from the World War I nickname for the MG 08, which was produced at the Spandau Arsenal.

A semi-automatic firearm, also called a self-loading or autoloading firearm, is a repeating firearm whose action mechanism automatically loads a following round of cartridge into the chamber and prepares it for subsequent firing, but requires the shooter to manually actuate the trigger in order to discharge each shot. Typically, this involves the weapon's action utilizing the excess energy released during the preceding shot to unlock and move the bolt, extracting and ejecting the spent cartridge case from the chamber, re-cocking the firing mechanism, and loading a new cartridge into the firing chamber, all without input from the user. To fire again, however, the user must actively release the trigger, allow it to "reset", before pulling the trigger again to fire off the next round. As a result, each trigger pull only discharges a single round from a semi-automatic weapon, as opposed to a fully automatic weapon, which will shoot continuously as long as the ammunition is replete and the trigger is kept depressed.

<span class="mw-page-title-main">Semi-automatic pistol</span> Type of pistol

A semi-automatic pistol is a handgun that automatically ejects and loads cartridges in its chamber after every shot fired. Only one round of ammunition is fired each time the trigger is pulled, as the pistol's fire control group disconnects the trigger mechanism from the firing pin/striker until the trigger has been released and reset.

A repeating rifle is a single-barreled rifle capable of repeated discharges between each ammunition reload. This is typically achieved by having multiple cartridges stored in a magazine and then fed individually into the chamber by a reciprocating bolt, via either a manual or automatic action mechanism, while the act of chambering the round typically also recocks the hammer/striker for the following shot. In common usage, the term "repeating rifle" most often refers specifically to manual repeating rifles, as opposed to self-loading rifles, which use the recoil, gas, or blowback of the previous shot to cycle the action and load the next round, even though all self-loading firearms are technically a subcategory of repeating firearms.

<span class="mw-page-title-main">Selective fire</span> Firearm adjustment

Selective fire, or select fire, is the capability of a weapon to be adjusted to fire in semi-automatic, fully automatic, and/or burst mode. The modes are chosen by means of a selector switch, which varies depending on the weapon's design. Some selective-fire weapons have burst fire mechanisms to limit the maximum number of shots fired automatically in this mode. The most common limits are two or three rounds per trigger pull. Fully automatic fire refers to the ability for a weapon to fire continuously until either the feeding mechanism is emptied or the trigger is released. Semi-automatic refers to the ability to fire one round per trigger pull.

<span class="mw-page-title-main">Magazine (firearms)</span> Ammunition feeding device of a firearm

A magazine, often simply called a mag, is an ammunition storage and feeding device for a repeating firearm, either integral within the gun or externally attached. The magazine functions by holding several cartridges within itself and sequentially pushing each one into a position where it may be readily loaded into the barrel chamber by the firearm's moving action. The detachable magazine is sometimes colloquially referred to as a "clip", although this is technically inaccurate since a clip is actually an accessory device used to help load ammunition into a magazine or cylinder.

Pump action is a type of manual firearm action that is operated by moving a sliding handguard on the gun's forestock. When shooting, the sliding forend is pulled rearward to eject any expended cartridge and typically to cock the hammer or striker, and then pushed forward to load a new cartridge into the chamber. Most pump-action firearms use an integral tubular magazine, although some do use detachable box magazines. Pump-action firearms are typically associated with shotguns, although it has been used in rifles, grenade launchers, as well as other types of firearms. A firearm using this operating mechanism is colloquially referred to as a pumpgun.

<span class="mw-page-title-main">Open bolt</span> System in firearms

A firearm is said to fire from an open bolt or open breech if, when ready to fire, the bolt and working parts are held to the rear of the receiver, with no round in the chamber. When the trigger is actuated, the bolt travels forward, feeds a cartridge from the magazine or belt into the chamber, and fires that cartridge in the same movement. Like any other self-loading design, the action is cycled by the energy released from the propellant, which sends the bolt back to the rear, compressing the mainspring in readiness for firing the next round. In an open-bolt gun firing semi-automatically, the bolt is caught and held at this point by the sear after each shot; and in automatic open-bolt fire, it's caught and held in this manner whenever the trigger is released. In contrast to this, in closed-bolt guns, the trigger and sear do not affect the movement of the bolt directly.

Blowback is a system of operation for self-loading firearms that obtains energy from the motion of the cartridge case as it is pushed to the rear by expanding gas created by the ignition of the propellant charge.

Rate of fire is the frequency at which a specific weapon can fire or launch its projectiles. This can be influenced by several factors, including operator training level, mechanical limitations, ammunition availability, and weapon condition. In modern weaponry, it is usually measured in rounds per minute or rounds per second.

A self-loading rifle or autoloading rifle is a rifle with an action using a portion of the energy of each cartridge fired to load another cartridge. Self-loading pistols are similar, but intended to be held and fired by a single hand, while rifles are designed to be held with both hands and fired from the shoulder.

<span class="mw-page-title-main">Trigger (firearms)</span> Mechanism that activates a gun

A trigger is a mechanism that actuates the function of a ranged weapon such as a firearm, airgun, crossbow, or speargun. The word may also be used to describe a switch that initiates the operation of other non-shooting devices such as a trap, a power tool, or a quick release. A small amount of energy applied to the trigger leads to the release of much more energy.

<span class="mw-page-title-main">Burst mode (weapons)</span> Automatic firing mode

In automatic firearms, burst mode or burst-fire is a firing mode enabling the shooter to fire a predetermined number of rounds, usually two or three rounds on hand held weapons to fifty or more rounds on autocannons, with a single pull of the trigger. This firing mode is commonly used in submachine guns and assault rifles. Other types of firearms, such as machine pistols, including the Heckler & Koch VP70 and Beretta 93R also have a burst mode.

The following are terms related to firearms and ammunition topics.

Self-loading firearm is a repeating firearm that can use some of the excess energy released from propellant combustion to cycle its action and facilitate loading of subsequent rounds of ammunition into the chamber, without needing the user to do any extra loading work with his hands.

<span class="mw-page-title-main">Repeating firearm</span> Firearms that can be discharged multiple times after a single ammunition reload

A repeating firearm or repeater is any firearm that is capable of being fired repeatedly before having to be manually reloaded with new ammunition into the firearm.

References

  1. 1 2 Carter, Gregg Lee (2012). Guns in American Society: An Encyclopedia of History, Politics, Culture, and the Law. ABC-CLIO. p. 53. ISBN   978-0-313-38670-1.
  2. "Maschinengewehr Modell 34 (MG34) General Purpose Machine Gun (GPMG)". militaryfactory.com. Retrieved 3 March 2017.
  3. "M240B - Machine Gun". armystudyguide.com. Archived from the original on 18 February 2017. Retrieved 3 March 2017.
  4. "Maintaining a Sustained Rate or Fire". thefirearmblog.com. 3 August 2012. Retrieved 3 March 2017.
  5. 1 2 3 4 5 6 Cutshaw, Charles Q. (28 February 2011). Tactical Small Arms of the 21st Century: A Complete Guide to Small Arms From Around the World. Iola, Wisconsin: Gun Digest Books. p. 250. ISBN   978-1-4402-2482-9.
  6. "Full Auto: Battlefield Necessity or A Waste of Ammo?". military.com. Retrieved 3 March 2017.